Comparative Toxicity Assessment of the Harm Reduction Potential of Tobacco-Free Oral Nicotine Products

      Oh, S.; Moses, S.; Aleksa, K.; Mehta, C.; Ma, D.; Coffa, B.

      Conference date
      Mar 11, 2024
      Conference name
      Society of Toxicology (SOT) Annual Meeting and ToxExpo 2024

      Background and Purpose: The growing use of flavored oral nicotine pouches (NPs) has prompted investigation into their potential health impact. Placed between the lip and gum, these products contain nicotine, flavorings, sweeteners, and plant-based fibers; they are considered harm reduction alternatives due to their low levels of toxicants compared to cigarette smoke. The present work assessed the ability of the ToxTracker® reporter assay to characterize the toxicological profiles of five NPs (ZYN®) and four Swedish snus (General®) products on the U.S. market and compare them to those of two reference tobacco products.

      Methods: ToxTracker was used to profile NP products and snus products with different flavors and determine if they could be toxicologically differentiated from a reference American-style loose moist snuff product (CRP 2.1) and combustible reference cigarettes (1R6F). ToxTracker combines six fluorescent reporter cell lines that are specifically activated by different cellular responses associated with DNA damage, p53 activation, oxidative stress, or protein damage. Reporter gene activation is measured by flow cytometry, and cytotoxicity of the tested compounds is simultaneously determined by relative cell count. NPs and snus were extracted in dimethyl sulfoxide (DMSO) or complete artificial saliva (CAS), and CRP2.1 and total particular matter (TPM) from cigarette smoke were extracted in DMSO.

      Results: Cigarette smoke TPM extract induced cytotoxicity and GFP induction of reporter genes for Srxn1 (oxidative stress), Ddit3 (protein damage), and Btg2 (p53 activation) in both the presence and absence of metabolic activation. CRP2.1 extract did not induce cytotoxicity but increased GFP-Ddit3 expression. The snus extracts in DMSO had similar profiles to the CRP2.1 extract, but GFP-Ddit3 expression was lower and below the positive threshold for three of the four products tested. However, there was no clear induction of GFP-Ddit3 expression when CAS was used for snus extraction. None of the five NPs extracted in DMSO or CAS induced cytotoxicity or GFP expression, suggesting that NP were the least toxic of the tested products.

      Conclusions: This study provides valuable insights into the toxicological profiles of various oral nicotine products compared to cigarettes, highlighting the harm reduction potential of NPs. These findings contribute to the ongoing research on harm reduction strategies in nicotine consumption, emphasizing the importance of considering specific product types and their safety profiles. Further research is needed to understand the long-term effects and broader health implications of these emerging NP products.